Spacer control for phototypesetting system



March 1967 R. A. PROUD, JR., ETAL SPACER CONTROL FOR PHOTOTYPESETTINGSYSTEM 3 sheetssheet 1 Filed May '7, 1965 INVENTORS r $835 mm 4 3 508mmom! mm5 m ru MW ME mm. 09 EB 6528 wk 02 mo 6528 J w. 5m F200 wofiw 3 mm5.558 0253 SE E05: 2533, kw [IE 8 & m 1.] mm v Fzou 02m: r N, woEw $6;NHE m NF 55:8 3: Sim 3o; @1 /mv 55:8 km], E.

m E05: 9* oo. mm m! 1523 an 3 W mm RALPH A. PROUD,JR. a BY RICHARD c.O'BRlEN mOPOmJmw JOKHZOU oma ATTORNEYS M r 1967 R. A. PROUD, JR, ETALSPACER CONTROL FOR PHOTOTYPESETTING SYSTEM 3 Sheets-Sheet 2 Fild May '7,1965 EIZIS omvl HBNNI HELLHO'" N QE March7, 1967v R. A. PROUD, JR, ETAL.3,307,459

SPACER CONTROL FOR PHOTOTYPESETTING SYSTEM Filed May 7, 1965 '5Sheets-Sheet I5 FIG-4 7 United States Patent 3,307,459 SPACER CONTROLFOR PHOTUTYPE- SETTING SYSTEM Ralph A. Proud, .1113, Somerset, N.J., andRichard C.

OBrien, Huntington, N.Y., assignors to Harris-intertype Corporation,Cleveland, Ohio, a corporation of Delaware Filed May 7, 1965, Ser. No.454,157 3 Claims. CI. 95-45 This application is a continuation-in-partof U.S. application Serial No. 117,454, filed June 15, 1961, now U.S.Patent No. 3,183,806, issued May 18, 1965, for Photographic TypeComposition.

This invention relates to improvements in digital stepping motors and inspacer controls for phototypesetting machines, particularly with respectto digital controls and transducers operating to produce spacingmovements of photosensitive material in a phototypesetting machine.

In phototypesetting systems the characters to be reproduced aregenerated by photographic devices which project shaped light beams alongan optical axis or path onto photosensitive material. The characterimages are thus formed on the photosensitive material in succession, andat the desired size, and in order to space the characters, one fromanother, according to typographic requirements, it is necessary toproduce relative movement between the photosensitive material and theoptical path according to the spacing desired for each character as itis projected. Various systems have been proposed wherein this spacingoperation occurs either before or after the flash exposure whichproduces the character image. The present invention is applicable tosuch arrangements, but it is particularly useful in connection withphototypesetting machines where the latent photographic image is formedon the photosensitive material and the spacing movement occursthereafter, such as described in said application Patent No. 3,183,806.

The present invention relates particularly to controls for high speedstepping motors, and to their use with phototypesetting systems wherethe spacing movement occurs on some type of digital basis, in otherwords, the spacing movement between the photosensitive material and theoptical path is produced as a plurality of small spacing increments.Preferably these increments should be small enough that the differencebetween them is minute, for example, one system employs individualspacing increments of one-sixty-fourth of a pica (approximately 0.0026")and in order to obtain optimum speed from the machine it is desired tohave the ability to produce an exact number of such incrementalmovements, which number will vary according to the width require mentsfor different characters, within a short time. For example, machineswith which the present invention is concerned, can employ rotatingcharacter matrices, together with high speed light flashes and controlswhich will cause the exposure of a character for each revolution of thecharacter matrix disc. With the disc rotating for example at 2,400 rpm,or forty revolutions per second, and allowing time for acceleration anddeceleration, and time for the computation of the character width data,it will be appreciated that the time requirements on spacing controls ofthis type are severe, and therefore any improvement in the decelerationcharacteristics of the spacer controls and equipment will in particularbe of great ad vantage in improving the speed and reliability of thesystem.

Accordingly, the primary object of this invention is to provide animproved spacing control for phototypesetting machines.

Another object of the present invention is to provide a novel steppingmotor drive, which may be used for exv Patented Mar. 7,1967

"ice

ample, in producing spacing operations in phototypesetting machines,particularly including energy absorbing devices which will removekinetic energy from the spacing mechanism to improve the decelerationcharacteristics of such mechanism to enable the photographic operationsof the machine to proceed at an optimum rate.

A further object of the invention is to provide an improved energyabsorbing or braking mechanism for high speed, relatively low torquesystems, such as the spacing mechanism of a phototypesetting machine.

Other objects and advantages of the present invention will become moreapparent from the following description, the accompanying drawings andthe appended claims.

In the drawings:

FIG. 1 is a schematic and block diagram showing the overall arrangementof a typical phototypesetting machine to which the present invention isdirected;

FIG. 2 is a circuit diagram showing details of the character decoderwhich is incorporated in FIG. 1;

FIG. 3 is a circuit diagram of the brake control shown in FIG. 1, forcontrolling the operation of an energy absorbing system according to thepresent invention;

FIG. 4 is a perspective side view of a spacing motor drive and energyabsorbing mechanism according to the present invention;

FIG. 5 is an end view of the device shown in FIG. 4; and

FIG. 6 is a detailed view of the energy absorbing mechanism per se.

Referring to the drawings, which illustrate a preferred embodiment ofthe invention, FIG. 1 shows the general arrangement of aphototypesetting apparatus embodying the features of the presentinvention. The apparatus is controlled by a perforated code tape 10, oran equivalent memory or record, and this tape passes through a pair ofreaders 12 and 15. The direction of travel of the tape is such that itfirst passes through the reader 12 and then through the reader 15. Bothof these readers are preferably of a known type as shown in UnitedStates Patent No. 3,027,072, called a star wheel reader, or aconventional reader of equivalent function.

The reader 12 is arranged to ignore all code words (e.g., a completegroup of code perforations across the tape) on the tape except any ofthe three end-of-line codes, which indicate an accepted line, or arejected line, or a non-justified line. The output contacts of reader 12are connected through a cable 17 to an end-of-line decoder circuit 20.This circuit includes appropriate controls for the drive of the reader12, and thus will permit the reader to continue to pass tapetherethrough until one of the three aforementioned codes appears on thereader. At such time, reader 12 will stop on the appropriate code wordwhile the function operations dictatedby the code are completed. Thismay mean that reader 12 will hold on a code while an entire line isbeing composed.

The reader 15, termed hereafter the character reader, has its outputsconnected through a cable 25 to a separate character decoder circuit 30.The essential details of this circuit are shown in FIG. 2. The circuitincludes controls for the drive of reader 15, and these likewise arearranged to stop reader 15, among other reasons, whenever one of thethree. end-of-line codes appears in the reader. Therefore, reader 15will stop for example on the endof-line code for a previously composedline, the reader 12 will stop on the end-of-line code for the line whichis to be composed, and the portion or loop of tape between the readers,as shown in FIG. 1, will contain the information necessary to compose afull line of composition.

Details of the end-of-line decoder circuit 20 are unimportant forpurposes of explaining the present invention. Suffice to say that theoutput circuits from this decoder will pass through a cable 32, forexample as control voltages applied to one or mores wires in the cable,and the wires from the cable are connected to a length memory circuit(for example conventional memory circuits) which in turn is arranged topreset a length counter 37 upon command. This counter is part of ajustification computer which also includes a controlled flipflop FFI,connected to the length counter, and arranged to connect the output of a100 kc. pulse generator 33 to the length counter 37 Likewise, otherleads of cable 32 are connected to preset a word space memory circuit40, into which is set the number of interword spaces in the line beingcomposed, for purposes of justifying computation. The word space memorymay likewise include a conventional memory circuit, and is arranged topreset a word space counter 42 which cooperates with the length counter37 in making the justifying computation. Control over the justifyingcomputing operation is exercised by a control flip-flop FF2 which inturn switches on or off the l kc. pulse generator 45.

For purposes of simplification, the parts 35-45 are shown assubdivisions of an entire block 48, which will hereafter be identifiedas the justification computer. Its output is in the form of a number ofelectronic pulses passed through line St to the spacing control motor 57which is driven from the space control circuit 55. This motor andcircuit may be of the type disclosed in said application Patent No.3,183,806.

Whenever the character decoder circuit 30 receives the code for ajustified interword space, an appropriate signal is transmitted throughthe output line 58 of that circuit to the justification computer, andthis initiates the operation of the computer whereby the amount of spacenot occopied by characters in the line of composition, having beenstored in the length memory 35, is set into the counter 37, and isdivided by the number of interword spaces which are similarly stored inthe word space memory and set into counter 42. The resulting quotient isexpressed in terms of the number of spacing pulses from the justifyingcomputer output through line 56 to the space control circuit 55.

In a similar manner, the cable 32 contains leads arranged to preset aleading memory circuit 60 which in turn is arranged to set up a leadingcounter 62 controlled by flip-flop circuit FF3. The output of thiscircuit is through lead 63 from the pulse generator 64 comprising partof the leading computer indicated generally at 65. The output line 63provides an input to a leading control circuit 66, comparable to thespace control circuit 55, as alsodescribed in the aforementioned PatentNo. 3,183,- 806. This circuit controls the leading drive motor 67.

The tape 10 is shown in FIG. 1 as a conventional pen forated paper tapehaving eight channels for information, whereby a so-called eight-bitcode word can be used for recording purposes. These channels areindicated by the letters (1-11, and further reference thereto will bemade with regard to the particular channel, for example, tile. The tapeis advanced by a sprocket wheel (not shown) incorporated in the reader,it being understood that this reader construction is generally the samefor both readers 12 and 15. The drive sprocket has a suitable steppingdrive which causes a stcp-by-step advance of sprocket wheel, wherebysuccessive code words on the tape can be presentedto the star wheelreading apparatus. It will be understood that a code word comprises acorresponding area in each of the channels 10ah, preferably alignedacross the tape, and each code word will comprise a bit of informationfrom a channel according to presence or absence of a hole in the tape.

For each channel there is a reading star wheel mounted on acorresponding lever arm in the reader. Each lever arm has acorresponding contact arm 8411-8411 (FIG. 2), and these arms formelectrical circuit contacts each of which moves between relatedstationary contacts, identified as contacts a1 and 856i through 85728and 851%. These are shown in FIG. 2 on the input side of the characterdecoding circuit. The reader, therefore, will present outputs on thesecontacts according to the position of the corresponding star wheel, andfor every code word there will be a possible completed circuit througheach lever arm 84a-84h, differentiating between presence and absence ofa hole. Not all of the available output circuits are required, however.Note in FIG. 2 that no circuit is used for 1 5, '6, or 7.

Each time the reader 15 reads a code word, it will decide this code wordand distinguish between a character identification (or characterselection) code and a function controlling code. Basically, thedifference between these two types of codes is determined by thepresence or absence of a hole in the channel 10h, i.e., an 8 or dsignal.

Referring to FIG. 2, it will be noted that such a condition isrepresented by a completed circuit between the contact arm 34h and the dcontact, identified as 851%. Presence of an E signal (no hole in channel1011) will determine that the code word pertains to selection of acharacter. Conversely, presence of an 8 signal determines that the codeword is for some function control. Various ones of the functions arenoted as legends over the corresponding circuit output lines shown inFIG. 2. For example, the 5.0.1.. (end-of-line) circuit, which is theen-d-of-line signal, is represented by completed circuits from T, 2 and8. These are the significant digits of the e-nd-of-line code word.

Assuming for purposes of explanation that a character code is presentedto the reader 15, then appropriate signals will be presented on one ormore of the character code output circuits which are identified in FIG.2 as a, 100b, 1000, 100d, little, 100 and .ltlflg. Each of the decodingcircuit lines is connected through a transistor amplifier, one of whichis shown schematically at 102. The seven selection output lines passthrough cable to the character selector circuit 108. This circuit iscontrolled by the code reading photocells 110, as more fully explainedin said Patent No. 3,059,219, and the character elector circuit in turncontrols the function of a spark control unit 112 and a flash controlunit 113,

These units are separate triggering circuits, the spark control unitbeing connected to the electrodes 115 to cause a spark to jump the gaptherebetween and produce an instantaneous flash of light when thedesired character passes the projection station, indicated by thedot-dash line 116 which shows the optical axis of the system.

Rotating continuously at fairly high speed, e.g., 2400 r.p.rn. acrossthe optical or projection path, is the character disc 120 which ispreferably an opaque plate-like member having the individual charactersformed as transparencies such that a shaped light beam is formed by thelight passing through the selected character. The timing of the flash isof course precise and of such short duration that the character imagebearing light beam is effectively stationary. This beam passes throughthe font selector prism system 122, as described in United States PatentNo. 3,099,945, and thence through the size controlling lenses 125. Fromthese lenses the character image bearing beam passes through an opticalfiat 127, or the like, which may be pivoted between two positions by thespace controller solenoid 128, as described in said Patent No.3,183,806, and thence the image is focused on the photosensitivematerial 130, which may be film or paper draped over and controlled bythe spacing carriage 132. This carriage is moved transversely to theoptical system by the spacing control motor 57 through the rack andpinion drive 133. Leading movements of the photosensitive material,i.e., vertically, are provided through the elongated gear 134 drivenfrom the leading control motor 67.

As soon as a character image is recorded on the photosensitive material,spacing movement of this material is provided by the controlling motor57. Information for this purpose is derived from the character unitwidth code or data on the disc 120. This code is read by flashing theelongated light tube 140 under control of the flash unit 113, at thesame time that the character is photographed. A unit width code is thusprojected to the bank of code reading photocells 142, and their outputsare fed through cable 144 to the space computer 145. This computer isprovided with a control flip-flop FF4 and a pulse generator 146, andwhich includes a separate input through cable 150 from a drum typeselector switch 152 which is coupled to the lens positioning controller154, these parts in turn being under control of the size control circuit95.

As is explained in greater detail in United States Patent No. 3,141,395the result is a burst of electronic spacing pulses which are transmittedalong the spacing circuit line 148 to the space control circuit 55. Thenumber of these pulses is related to the actual width to be alloted tothe character image just photographed, in terms of picas and fractionsof a pica, or piclets.

It should be noted also in connection with FIG. 1 that there is a secondcharacter disc 120a, and it may be moved alternatively into the opticalsystem under control of a disc shifting apparatus 155 which is driven bydisc shifting pneumatic cylinders, one of which is shown at 156.Operationof these cylinders is controlled by a disc change controlcircuit 160 operating from signals passing through cable 162 which leadsthe decoder circuit 30.

In explaining the tabulating and leader insert controls, it is desirableto mention certain features of the operation of the photographicmachine. Thus, with reference to FIG. 1, and as previously mentioned,when a control tape is fed into the readers 12 and 15, the reader 12passes over code words except the end-of-line codes, and when one ofthese codes appears to the reader 12, it stops and maintains this codein a reading position. The tape in the meantime builds up as a loopbetween the two readers, and when the reader 12 reaches the end-of-linecode for an acceptable line, it sends a go ahead signal to the readerwhich in turn proceeds to read all of the code words, one at a time.

Each time the reader 15 reads a code word it transmits the appropriatecode to the character decoder circuit 30, and as an incident to thisoperation a tape step signal is sent to the reader and the reader stepsto the next code and waits. In the meantime, the decoder circuitoperates to determine whether a character selection code or a functioncontrol code is presented, and routes the information accordingly eitherto the character selector or to the appropriate one of the functioncontrol circuits. Among these circuits is the tabulate circuit 175. Assoon as the character selection operation, or the function operation iscomplete, then a signal is transmitted to the character decoder which inturn generates a tape read pulse or signal to the reader 15.

The read pulse amplifier 170, shown schematically in FIG. 2, has aninput 171 through which the feedback or go ahead pulse is received, andhas two separate output lines 172 and 173 which both transmit the taperead pulse. Line 172 leads to the common connection of the first sevenstations of the reader and line 173 leads to a stepping switch in thesize control circuit 95. Since all operations of the machine require anoutput pulse through either the 8 or 8 line of the character decoder(note FIG.

2), normal operation of the machine is suspended for the pulse over line172 is accompanied by a simultaneous read pulse through line 173.

The present invention is particularly concerned with operation of thestepping motor 57 in performing the spacing operations according topulses transmitted to it from the pulse generating means which may bepulse generators in any one of the space computers 145, thejustific-ation computer 43, or the tabulate control 175. These pulsesare transmitted to the space control 55 on the lines 148, 50 and 176,respectively. As shown in FIG. 1, each of these lines also is directedto anOR gate circuit 180. Whenever spacing pulses are being transmittedto the space control 55, a 13.0 level is established in the OR gate, butwhen the spacing pulses stop, this level drops and accordingly a signalis transmitted over line 182 to the brake control circuit 185. Detailsof this circuit are shown in FIG. 3, and are explained hereafter ingreater detail. In general, the operation is such that the brake controlcircuit applies power momentarily to an energy absorbing mechanism whichis incorporated in the output of the stepping motor 57. For purposes ofsimplification in terminology, the mechanism 19% is termed a brake, butit should be understood that the function of this mechanism is to absorbenergy from the stepping motor output momentarily, but not to lock thatoutput in position. When the stepping motor comes to rest, the brakemechanism 198 is not applied, and the ultimate po sition of the steppingmotor output, and hence of film carriage 132, remains under the controlof the stepping motor, as described in said Patent No. 3,183,806.

The structure of the brake control mechanism is shown in greater detailin FIGS. 4, 5 and 6. The stepping motor 57 is mounted on a supportingframework 200, and the motor output shaft 202 extends to a toothedclutch 2ti5. This clutch is normally engaged, as shown, but it can 'beopened by causing the lever 206 (FIG. 5) to pivot around a pivot pin207, carrying the output portion 208 of the clutch, and its shaft, outof engagement with the input side. This movement may be accomplished byenergizing a clutch solenoid (not shown). The output member 203 of thetoothed clutch thus functions to rotate the pinion 133a of the rack andpinion drive 133 which moves the film carriage 132 (FIG. 1).

On the stepping motor output shaft 202 there is fixed a brake discmember 210. This disc preferably is constructed of a soft iron, and isprovided with a rather heavy chrome plating. For example, the platingmay be in the form of 0.001 inch. The disc 210 thus forms the rotorportion of the brake mechanism 190.

The stator of the brake system is formed as an electromagnet including ahorseshoe-shaped armature 215 fastened to a carrying bracket 216 whichin turn is carried by a relatively thin spring-like plate/217. Thisplate is fastened at its upper end to the bracket member 218 which isincorporated in the frame member 2%. Thus, the armature 215 and theremainder of the stator structure is somewhat movable toward and awayfrom the disc 210, for purposes of compliance. The brake coils 220 arewound on the pole pieces of the armature 215, as shown in FIGS. 5 and 6,and are provided with power leads 222. Preferably, the armature isformed as a laminated material since this serves to reduce the electricresponse time of the brake system by reducing eddy current elfects. Thesame resultcan be obtained by use of a powdered iron armature structure.The face of the stator pole pieces, as shown in FIG. 5, is thus a flatterminus of the plurality of la-minations. These may be arranged eitherhorizontally or vertically, or in some other convenient'rnanner,although a vertical lamination direction is shown.

With reference to FIG. 3, a spacing operation is underway, a DC. levelis established as an output of the OR gate 180. This is applied to theinput line 182 of the brake control, as shown in FIG. 3. This signal iscoupled to the base circuit of the transistor Q1, which together withthe resistors and capacitors and the dio CR1, form an edge sensitiveamplifier. When the output level in line 182 falls, as a result ofcessation of a spacing operation, there is an immediate output from thisamplifier circuit through C1 to a one-shot multivibrator circuitprovided by the transistors Q2, Q3, and the diodes, capacitors, andresistors connected therethrough, as shown. The output of thism-ultivibrator is coupled to the base of the power transistor Q4.

Thus, an output pulse from the multivibrator will cause the powertransistor Q4 to conduct and apply power through the brake coil outputlines 225 and thence through the lines 222 to the coils 220 of the brakemechanism. The time constants of the circuit are such that the pulsefrom the multivibrator circuit is suflicient to energize the brakemechanism for approximately ten to fifteen milliseconds. It has beenfound that applying a retarding force through the brake mechanism forthis amount of time is adequate to obtain a substantial decrease in thetime required for the stepping motor output to come to a complete stop.

For example, without the energy absorbing or braking mechanism,measurements of the time required for the stepping motor output tostabilize at its final position indicated that approximately one hundredmilliseconds were required in order to damp the stepping motor output.It should be recalled that this motor is required to step at up to threehundred steps per second, and that the ultimate position which it is toattain at the end of a spacing operation is dependent upon theelectromagnetic field resulting from a particular energization (as topolarity) of the motor windings. This system is fully explained in saidPatent No. 3,183,806. It is possible that the output may actuallyoverrun slightly, and then return to the ultimate desired position. Inthis regard, it should be kept in mind that the movements referred tohere are very slight, since each step produces only a small actualmovement of the film carriage. With the present invention it has beenpossible to reduce the settling time of the system to approximatelytwenty milliseconds, or in other words this time time has been decreasedto about onefifth the previous time required. The pulse applied throughthe brake coils 220 is shaped to give a short rise time and a relativelyslower decay time. Thus, the brake mechanism engages quickly, butreleases somewhat more slowiy, thereby assisting in quiescing themovement of the stepping motor output as it seeks its proper position.

The present invention, therefore, provides a means for removing kineticenergy from the spacing system of a phototypesetting machine, therebyobtaining a net gain in time during each spacing operation which, duringthe course of several hours of operation of the machine, may amount to asubstantial span of time. More important, the system assures that thefilm carriage is stabilized in the desired position before the nextcharacter is Photo graphed. This system thus contributes to the accuracyof placement of the character images at the high speeds required ofcommercial phototypesetting systems.

The invention is its broader aspects also is concerned with the controlof stepping motors used for other purposes, such as driving a high speedtape reader, or in any device where digital or stepping drive isrequired with rapid deceleration.

While the form of apparatus herein described constitutes a preferredembodiment of the invention, it is to be understood that the inventionis not limited to this precise form of apparatus, and that changes maybe made therein without departing from the scope of the invention whichis defined in the appended claims.

What is claimed is:

1. In a phototypesetting apparatus having means for projecting characterimages of different Widths along a common path and a means for mountingphotosensitive record material in an image plane over said projectingmeans for recording the images to produce lines of composition, andincluding spacer means operative to cause spacing movement between saidmounting means and said common path, said spacer means incorporating astepping motor having an output member adapted for movement in apredetermined number of equal steps for causing spacing movement indigital fashion and for maintaining its position solely through theapplication of an electrical field within said stepping motor, means forgenerating digital spacing information representing spacing movementsdesired, and circuit means operative to direct said digital spacinginformation as control pulses to said stepping motor to cause operationthereof in a predetermined number of steps; the improvement comprising adeceleration control circuit responsive to said circuit means togenerate a signal indicating the cessation of operation of saidgenerating means, a selectively operable energy absorbing mechanismconnected to said position control member for retarding movementthereof, and a circuit controlling the operation of said energyabsorbing mechanism to render it operative at each cessation ofoperation of said generating means for absorbing energy imparted to saidoutput member and thereby damping oscillations of said output member toimprove the damping time characteristics of the spacer means.

2. Apparatus as defined in claim 1, wherein said circuit controlling theoperation of said energy absorbing mechanism includes a multivibratorcircuit operatively connected to produce a single energizing pulse tosaid energy absorbing mechanism in response to an output from saiddeceleration control circuit, such pulse having a relatively rapid risetime and relatively slower decay time to cause said energy absorbingmechanism to engage quickly against further movement of said motoroutput member and to release more slowly to enable said motor outputmember to achieve its final position under the control of the electricalforce field than existing within said stepping motor.

3. In a phototypesetting apparatus having means for successivelyprojecting character images of different widths along a common path anda means for mounting photosensitive record material in an image planefor recording the images in succession to produce lines of composition,spacer means operative to cause relative spacing movement between saidcommon path and said mounting means, an electrical stepping motor havingan output rotor shaft, an output connection between said rotor and saidspacer means, said motor including means for creating an electricalforce field movable one step at a time in response to a control pulseand operative on said rotor to maintain precise positioning thereof andto move said rotor in precise stepped spacing increments, meansgenerating digital spacing information for each character image in theform of a number of pulses corresponding to the Width of such imageduring the time interval between photographing successive characterimages, space control means directing such pulses to said motor toprovide stepby-step spacing movement of said spacer means according tothe spacing information for each related character image, a brakecontrol circuit means operative to provide an output signal indicatingcessation of operation of said pulse generating means, and an energyabsorbing damping mechanism connected to said rotor shaft and controlledby said brake control circuit means to exert a momentary braking forceon said rotor shaft at the terminal portion of each spacing operation tominimize oscillations of said rotor shaft and thereby to improve thedamping time characteristics of the spacer means.

References Cited by the Examiner UNITED STATES PATENTS 3,088,388 5/1963TREDOPP 9531 3,183,806 5/1965 OBRIEN et al 9531 JOHN M. HORAN, PrimaryExaminer.

1. IN A PHOTOTYPESETTING APPARATUS HAVING MEANS FOR PROJECTING CHARACTERIMAGES OF DIFFERENT WIDTHS ALONG A COMMON PATH AND A MEANS FOR MOUNTINGPHOTOSENSITIVE RECORD MATERIAL IN AN IMAGE PLANE OVER SAID PROJECTINGMEANS FOR RECORDING THE IMAGES TO PRODUCE LINES OF COMPOSITION, ANDINCLUDING SPACER MEANS OPERATIVE TO CAUSE SPACING MOVEMENT BETWEEN SAIDMOUNTING MEANS AND SAID COMMON PATH, SAID SPACER MEANS INCORPORATING ASTEPPING MOTOR HAVING AN OUTPUT MEMBER ADAPTED FOR MOVEMENT IN APREDETERMINED NUMBER OF EQUAL STEPS FOR CAUSING SPACING MOVEMENT INDIGITAL FASHION AND FOR MAINTAINING ITS POSITION SOLELY THROUGH THEAPPLICATION OF AN ELECTRICAL FIELD WITHIN SAID STEPPING MOTOR, MEANS FORGENERATING DIGITAL SPACING INFORMATION REPRESENTING SPACING MOVEMENTSDESIRED, AND CIRCUIT MEANS OPERATIVE TO DIRECT SAID DIGITAL SPACINGINFORMATION AS CONTROL PULSES